Charge controller not allowing 48V system to discharge below 45v. Alarms at 46V, shuts down at 45V.

[Sun_Dried_Toad]

"Bright solar" brand: MPPT-5KW 48VDC 60A charge controller.
8x qcell 305w panels, wired series parallel 4&4.
8x Trojan T-1275 12v lead acid batteries, series parallel 4&4 for 48VDC.

just made the switch to full solar last Sunday.

The issue we are having is that we are losing power when early in the morning when we are just getting up and getting ready for work. The controller does not allow the batteries to discharge below 45V. Being that these are deep cycle batteries, I feel that they should be allowed to cycle down to at least 30V if not even 28V before any alarms or shutdown happens.

The controller shows a low battery icon, sounds alarm then eventually shuts down, right before the sun can begin charging our array. I checked the batteries, each morning, and they still have 46~ish volts at the time of alarm and shutdown.

The batteries are fully charged when we go to bed. the first night they tested 54V when we went to bed. second night they tested 48.5V at bedtime, and then the 3rd night I showed 49.8V at bedtime.

to get us by until we find a resolution, we are switching it over to grid priority mode when we go to bed, then when I get up in the morning, I switch it back to PV and battery mode.

The manual to our "Bright Solar" brand controller makes no mention of voltage cycle programming or settings. for those not familiar with the "BR Solar" units, they appear to be a clone of Victron, at least in color, looks, and style. I have contacted the person who sold the unit, he is trying to find an answer, but has been unsuccessful for two days. he has an identical test unit set up at his office/shop as he tries to troubleshoot this issue.

one other small issue we are having, is that two of our clocks have started running slow since we switched. both are brand new appliances. one is a Whirlpool microwave and the other is a GE oven/range. Both were purchased about 6 months ago. both worked fine prior to the solar switch. we have one other clock on our range hood that works normally. to recap, that two out of three clocks suddenly running slow. all thee appliances are brand new, all are digital, and all worked normal prior to solar.

I am hoping that these are both small and curable issues.

 

[Picasso]

You expecting to take them way way to low. 47.5 is as low as you should go. The alarm is attempting to prevent you from killing them and doing its job.

 

[snoobler]

The issue is you don't know what you're doing, and you don't understand the limitations of your system.

You are hammering the shit out of your batteries. They're probably not going to last a year if you keep this up.

A 48V battery is completely depleted at 42V. Your inverter will stop functioning due to low voltage somewhere around there. Per @Picasso you should further limit your discharge to about 50% of the total capacity, or you will destroy them in a year or two.

I recommend you digest the following two resources:

Trojan Battery | Battery Maintenance

The key to achieving optimum performance and long battery life is to follow a regular care and maintenance program. Read our tips for high performance battery maintenance.

www.trojanbattery.com

https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

I have 8 T-1275 as well in the same configuration. They have a 0.13C charge upper limit. Your charge current should be limited to 39A. Higher will damage the battery bank. Your panels could put out up to 51A, which should not be allowed to hit the battery.

You should be charging your batteries to 59.28V to get fully charged with a a tail current of 6A and a float of 52.8V.

Assuming you get AMAZING sun, you're unlikely to generate more than about 12.2kWh of energy daily. That's about 40% the average U.S. household.

Note that my 8X T-1275 and 3kW of solar provide just enough to run a 5th wheel RV running the furnace blower overnight. Likely less use than a house.

Until you have a clue about your system and the function/capabilities of your batteries, I recommend you absolutely, positively do not discharge from the batteries and stay on grid power.

 

[Sun_Dried_Toad]

Alright. that's a solid answer.

So, it sounds like the issue should be solved by adding more batteries, and if necessary, more PV panels.

How many batteries can my current array of 8 QCELL panels wired in parallel/series (4 & 4) charge and maintain?

My current array is putting out around 150V at a theoretical 18 amps, at maximum potential. I say theoritcal amps, as my current clamp/multimeter does not read DC amps, only AC. I do have a controller PLC menu that shows me my amperage, but I have not looked at it during peak sun yet. during my first 2 days, I did not know about that menu screen, and was only using my multimeter.

I have been told that my current array can handle an additional 4 batteries, but I have also heard from another source that I may already be at maximum charging capacity with my current array. I would like a second opinion from this community.

If adding PV cells is needed, I have an option to get 4 QCELL G5 315W panels at a much better price than I can get 4 additional G4 305W panels. So that brings me to my next beginner question: can I wire in 4 G5 qcell 315W panels in with my current 305W panels? If so, can I wire them in as their own parallel circuit? meaning that I wire all 4 of the 315W panels in series, then join them parallel to the existing arrays, then on down to my Hybrid MPPT controller? I know there are drawbacks to wiring in mixed wattage panels together. I don't mind that I would lose some of my higher efficiency from my 315W panels by wiring them in with 305's. I can accept that, but is there any risk of harm to the system?


Additionally, I see that SNOOBLER is mentioning the 51A potential output from my array. Each panel is rated for 9.35 A at maximum power. It is my understanding that since my panels are joined 4 parallel to 4 series, I am only going to produce around 18 to 19 Amps. In addition to that, I thought that charge distribution to my battery bank is entirely regulated by my charge controller. I was under the impression that so long as I do not deliver too much amperage to the controller, it will do it's job and regulate all voltage and amperage distributed to the battery bank.

 

[snoobler]

No. Before you start looking at panels or batteries, you need to establish what's going on and take appropriate actions.

1. Are your batteries being properly charged to full every day?
2. What is your available solar (link #5 in my signature)?
3. Does your usage exceed the energy you can capture during a given day?
4. Was this system sized based on an energy audit?
5. Have you altered your habits to ensure that higher power items are avoided when running on battery power alone?

Concerning the "51A" statement:

The high voltage/low current from the array is converted to the lower battery voltage and higher current, power in = power out. Varray * Iarray = Vbattery * Ibattery

8*305W = 2440W

2440W/48V = 51A

EDIT:

Is this your unit?

China Solar Inverter With Controller Built-in Manufacturers, Suppliers, Factory - Solar Inverter With Controller Built-in Made in China - Bright Solar

As one of the most professional solar inverter with controller built-in manufacturers and suppliers in China, we're featured by quality products and good service. Please rest assured to buy solar inverter with controller built-in made in China here from our factory.

www.brsolar.net

 

[Sun_Dried_Toad]

My best attempt at informed answers to the above questions:

1. According to multimeter batteries at 50.6 V after a full day of sun, following an excessive drain to low battery alarm the night before. When tested after a full day of sun WITHOUT being excessively drained the night before, it is showing 55.5 V

2. Average sun hours of 5.5 in a nearby city, this month.

3. I believe that we are capturing sufficient energy for our use during the day. This based upon seeing batteries at full charge when the sun goes down, not having any outages during day, and fact that our home is unoccupied all day, thus reducing consumption. We also make it through our evening hours with usage without problems, above 48v threshold. We switch back to grid priority (and battery charging) before we go to bed. This allows us to start each day with full battery charge.

4. System was sized based upon an energy audit. I have our sales person a complete list of all of our appliances. The list was detailed with wattage (or amperage) listed upon data plates of all items. Any items without specific info available on a tag was researched on his end to find a close approximation. Those values were then applied to approximate expected daily/hourly usage of said items. According to his assessment, this system was appropriately sized. It did not have a huge amount of wiggle room, but with us adjusting our usage to be more power conscious, it should have been well within parameters.

5. The only items we would be running when on battery power are: one kitchen refrigerator/freezer, one kegerator/refrigerator, one small chest freezer, two fish aquarium pump/aeration systems, modem & WIFI router, 2 phone chargers, a small HEPA filter and occasional automatic cycling of our 110v central heater blower fan (furnace is gas) thermostat is set to 64degrees, and it has not been particularly cold in our area lately, so it does not run a lot.


All of this system sizimg and power usage information was guided by my solar system sales representative. While I am learning as much as I can, as fast as I can, about home solar systems, I must rely on the information that is presented to me as being correct, until shown to be incorrect.

 

[Sun_Dried_Toad]

No. Before you start looking at panels or batteries, you need to establish what's going on and take appropriate actions.

1. Are your batteries being properly charged to full every day?
2. What is your available solar (link #5 in my signature)?
3. Does your usage exceed the energy you can capture during a given day?
4. Was this system sized based on an energy audit?
5. Have you altered your habits to ensure that higher power items are avoided when running on battery power alone?

Concerning the "51A" statement:

The high voltage/low current from the array is converted to the lower battery voltage and higher current, power in = power out. Varray * Iarray = Vbattery * Ibattery

8*305W = 2440W

2440W/48V = 51A

EDIT:

Is this your unit?

China Solar Inverter With Controller Built-in Manufacturers, Suppliers, Factory - Solar Inverter With Controller Built-in Made in China - Bright Solar

As one of the most professional solar inverter with controller built-in manufacturers and suppliers in China, we're featured by quality products and good service. Please rest assured to buy solar inverter with controller built-in made in China here from our factory.

www.brsolar.net

Yes. That is our unit.

Despite it listing 220v on the panel, it has been reprogrammed for American homes to put put 110v.

 

[snoobler]

1. You need to confirm that the charge controller is programmed to use the voltages I provided. The unit should charge the batteries to 59.28V and hold that voltage until the charge current drops to 6A. At that time, the bank is fully charged, and it should maintain the float voltage of 52.8V provided there is sufficient solar to meet loads. If you find that you have excessive bubble-over or require frequent re-watering, reduce absorption voltage from 59.28V to 58.8V. I had to do this to keep mine from bubbling over.
2. Nice. That means you should generate 5.5h * 8 * 305W = 13.4kWh/day - almost 1/2 the average U.S. household.
3. Belief is unreliable. Data is better. If your unit reports daily kWh usage or solar harvest, that may give you an idea if your unit is sized properly. If you're not fully charging your battery every day using the above voltages, you are limiting yourself.
4. That's good to know. Too many people go off half-cocked and just make guesses. You need to assess if your usage patterns actually mirror the audit results.
5. The 3 refrigeration units may be consuming 4-5kWh of your daily production capability. You may have no wiggle room at all. Our RV furnace blower required a full 100W to run it, and I would assume that yours is much larger.

The fact that you are nearly completely depleting your batteries nightly demonstrates that the information your solar rep provided is in question.

For FLA batteries, if you truly do have a daily consumption of about 12-14kWh/day, your battery should be 2X that to allow for discharges to not be below 50% for longevity. You currently only have 14.4kWh of storage. Keeping those T-1275 above 50% charge will likely get 5+ years out of them. Cycling them below 50% will probably wear them out in no more than 2 years - likely even faster.

Every day you cycle your batteries, you lose a little. Thus the same usage each day requires more and more of the % total capacity of the battery accelerating the deterioration. In other words, Day 1 may only use 40.0% of the total capacity, but day two may use 40.01%, day 3, 40.02%, etc.

Step 1 is to determine if you are fully charging your batteries daily based on the battery absorption voltage and tail current.
Step 2 is to establish your actual daily energy usage. Hopefully, you can gather this information from data the unit will provide. You may find that you need 2X the battery capacity and another 20% of solar (your unit can't handle any solar beyond 3200W).

 

[Sun_Dried_Toad]

Ok. Here are some updated stats, collected on my first day off since switching to solar system. I have been home all day, and have checked throughout the day with both my multimeter and the display panel menu on the unit.

Today has been completly overcast clouds. Solid grey sky, no visible sun or gaps in clouds. This is highly unusual for our area of the country. We are generally clear sky 75% of the time, light scattered clouds 15% of the time, rain less than 5% decent cloud cover 3% and solid cloud cover or overcast 2% or less. All by my estimate.

All day, unit has shown battery to be at 100% charge on display panel.

Load has shown between 4% to 10% mostly around 5% to 6%

Voltage of batteries has shown (multimeter) between 50.9 to 49.9 throughout the day.

I had switched unit from grid priority back over to PV and battery at about 7:30 am. That is about the time that sun begins to start to show at horizon. I cannot remember what the battery voltage was at this time, but I would assume it was around 54ish. I can reconfirm this in the morning when I get up.

During this day there are the items that have run:
2 fish aquarium pumps
1 load laundry mach. 3.2A I think? (dryer is not on solar) I have written down 384W.
Kitchen refrigerator (5.3A 110v) large 1yr Samsung
Beer refrigerator (6.5A 110v) medium/small GE 2yrs old
Deep freezer small (1.7A 110v) 5cuF GE 10yr old
Wi-Fi router
Modem
I have turned on one or two lights a few times today. Each less than 3 minutes.
TV for 1 hour this AM. 70" Samsung 6mos old.

My heater has not run today, so that means the blower fan has not come on either.

Attached photos of various menus on unit. The wattage photo that looks odd says 282w. The last "2" was changing as the photo snapped, so it looks odd.

These photos were taken at 3:30 pm

About 1hour after these photos were taken clouds broke a bit. Wattage jumped to a little over 400 and the amps were over 8. Volt input was up over 130. All of that at 4:30 pm sun.

 

[Sun_Dried_Toad]

Here is a rough chart the my solar rep and I compiled when I was building this system.

 

[snoobler]

Your attachment is not legible. Please review its quality as though you have never seen it before and don't know what it says.

100% charge has no meaning unless you know that the representation is correct. If it's simply voltage based, it's an extremely poor and inaccurate indication of state of charge (SoC).

A proper SoC is obtained from "counting current." The device is programmed with: 1) the battery capacity and 2) the criteria for 100% SoC. It then determines the state of charge by counting the net current in and out of the battery to determines how much remains.

I can say with near 100% certainty, your battery was not at 100% SoC with voltage readings of 50.9 to 49.9V UNLESS it is: 1) purely voltage based, or 2) improperly programmed.

Please answer the following:

1. What is the boost/bulk/absorption voltage set to?
2. What is the float voltage set to?

Please note that boost/bulk/absorption are all terms for the same parameter. You are looking for only one of them.

 

[Sun_Dried_Toad]

poor quality display menu photos explained in text below, in order from left to right, top row, then bottom row.

1. 126v input (from PV)
2. 5.7A input (from PV)
3. 282w (input/output not designated)
4. grid input "0" working mode [01] grid priority MPPT output 110v
5. grid input "0" working mode [01] grid priority Batt. charge lvl 100%
6. grid input "0" working mode [01] grid priority 60Hz output
7. grid input "0" working mode [01] grid priority system load 8%

as far as boost/bult/absorbtion rate... I will take my best guess at what the manual is trying to say. it's in written in a not-so-great translation to English.

I have it set to "charging voltage value" 55.2 "open lead acid" as per the pg 12 in the manual

I am not sure what the float voltage is set to. I don't know that it is discussed in the manual.

the manual does not seem to offer much in the way of detailed electrical operation, diagnosis or specific charging rate information.

I am having a hard time understanding exactly what is and is not discussed in the manual. it is pretty obviously a poorly done machine translation. combine that with me still being new to many of these concepts and terms... I am learning as fast as I can. I was told that this unit would be "plug and play" at the time of purchase, and that all the internal settings would be correct for the equipment, batteries and hardware sent.

I understand basic electrical theory and know how to use a multimeter and can troubleshoot and repair HVAC and other basic industrial and residential components, but am entirely new to solar systems. I have taken basic electrical training, but there are some new concepts here. battery charging, and power consumption rates are not something I deal with in detail. I do look at power consumption on various motors in my field of work, but it tends be in a simpler comparison of current vs name plate data for basic function or motor health diagnostic.

I will attach photos of the manual. I will begin at page 10, because most of what comes pg 9 and before is mostly just how to install, and display icons.

as best as I can tell, the only information that pertains to the questions you specified above, is on pg 11 through 13. page 14 has some word salad descriptions of the various grid priority mode, battery priority mode, and an energy saving mode. it is so poorly translated, that I'm having to take my best guess at what it is trying to say, and combine that with a few days of confirming whether I guessed right or wrong based upon it's performance.

It currently is set to "grid priority mode" so that the system tries to run only as a back up if the grid were to malfunction. In order to make it run battery priority during the day, I am simply turning the grid supply "AC input" off. in the evening, when the battery charge drops to 48 volts, I switch the AC input breaker back on, and our house runs on grid, while also charging the batteries fully.

 

[snoobler]

Again, your images are very difficult to read. I'm 50, and while I spent most of my life with perfect vision, I now require reading glasses.

What little I can glean gives me grave concerns with the suitability of the unit. In my opinion, it is worse than garbage. As much as I dislike Growatt and MPP Solar units, they would be a vastly superior choice.

If those are hard voltage limits, you 1) aren't fully charging your batteries and 2) are going to destroy them far sooner than they would be if properly charged. If they are some sort of average voltage where absorption is higher than that number and float is below it, then you might be okay.

Tomorrow, you need to spend time watching the display. Run the battery down below 50V and then ensure both grid and solar are available for charging. You need to note what the battery voltage does over time.

It should rise to a peak voltage, hold that voltage and then fall to something steady. Need to know the peak voltage and the steady voltage.

 

[Sun_Dried_Toad]

Thank you very much for taking the time to respond and educate me on this.

I will do as you have stated above.

It is running on grid priority now. It was discharged down to 48.7v when I switched the grid supply back on. I will take a voltage reading when it is charged in the morning.

When I do the discharge down to 50v, then charge back up to full, you say to "have both grid and solar available" does this mean that once I discharge down to 50v, I should turn on the grid supply for recharge during mid day, or should I allow the PV array to recharge and only use the grid supply if, for some reason, it does not charge in a certain about of time?

is there a certain amount of time I should be looking for during the recharge back up from 50v?

once it is back to "full charge" (whatever value that proves to be) do I leave it charging only on solar, or should it also leave the grid supply connected? if the grid stays connected, it is my understanding that the grid will remain primary, and the batteries/PV array will not contribute to the load, thus the batteries would remain at full charge and not experience any drain, regardless of any load present.

 

[snoobler]

This is what a proper charge profile looks like:





Blue is voltage, orange is current. This was today's charge profile.

The reason my blue line hits 60.68V and tapers off is due to temperature compensation. The battery temps vary by about 20-30°F per day, so the charge voltage decreases with increasing temperature. Your blue line will likely be flat after it hits its peak.

You can see the orange line taper off as the blue line decreases. This is the absorption or constant voltage phase. About 20% of the total capacity is charged in this phase under standard conditions. Both abruptly drop off as the current falls below the minimum and then they're fairly constant while in float mode (around 53V). Around 5pm, PV becomes unavailable and both drop. Note that the far right of the orange line is actually negative to reflect the load supported by the battery.

The goal in tomorrow's exercise is to establish if the battery is charging properly. In order to do that, I recommend you use grid power to ensure the system is fully charged as quickly as possible. Personally, I recommend you grab some form of entertainment (book, phone, tablet) you can engage in while sitting in front of the battery checking the voltage every 5 minutes or so for a couple hours. If you can record charge power or in watts or current in amps at the same time, that would be helpful.

I'll repeat a portion of my first post here again:

Until you have a clue about your system and the function/capabilities of your batteries, I recommend you absolutely, positively do not discharge from the batteries and stay on grid power.

To state it another way. Leave the unit in grid priority mode at all times unless engaging in diagnostic exercises.